Lightning arrester



March 20, 1945. E. J. .WADE

LIGHTNING ARRESTER Filed Hay 22, 1940 2 Sheets-Sheet l 11,1, 1 .l\/\/\/\\/VV\\\\ Inventor: Elmer` J. Wade, by W His Attorney.

March 20,'1945. El 1 WADE I LIGHTNING ARRESTER Filed May 22, 1940 2 Sheets-Sheet 2 Inventor Elmer` J. Wade,

j Hls Attorney lto a iixed Patented Mar. 20, 1945 LIGHTMNG ABBESTEB d. Mass., signor to Gen- Elmer J. Wade, Pittsel eral Electric Com York pany, a corporation of New Application May 22, 1940, Serial No. 336,576

9Clalms.

l This invention relates to lightning arresters, and more particularly to arresters of the are expulsion type.

This type of arrester generally comprises a hollow insulating tube of gas emitting material provided with a conductive metal electrode at each end, one of the electrodes being grounded support and the other electrode being spaced by a gap from an electrical conductor which is to be protected. One or both of the electrodes extend into the tube to provide an internal gap short enough to compel any discharge from the protective conductor to the grounded electrode to follow a path across the internal gap instead of a path between the electrodes along the outer surface o1' the tube. Upon the occurrence of a discharge through the tube the material thereof gives off a quantity oigas under the iniiuence of the arc heat and the evolution of this gas is so rapid that a high pressure is created inside of the tube to blow the arc out through one siderable length and with longer length tubes the spacing between the end electrodes is such that relatively high pressure are formed within the bore thereof so that in order to prevent excessive pressures the longer the bore the greater must be the inside diameter of the tube. With greater tube diameters the operation of the device becomes less efficient since the arc may strike between the electrodes in a spaced relation from the tube wall so that the heating thereof and the gas emission therefrom is materially decreased. Since the proper functioning of the device depends upon the emission of large quantities of gas, it is desirable that the arc be confined within a relatively narrow passage between opposed surfaces of gas emitting material.

It is therefore an object of the present invention to provide a new and improved electrical discharge device of the general type referred to which is suitable for protection of relatively high voltage lines, and which is reliable and eiiicient in operation.

For a better understanding of the invention, attention is directed to the following specification and the claims appended thereto taken inconnection with the accompanying drawings in which is an enlarged view in perspective of one detail of the structure and Figs. 4 and 5 are views partly in section of a lightning arrester constructed in accordance with a second modiiication of the invention.

I'he high voltage transmission line conductor Il, shown in Fig. 1, is secured by a metal clamp II to a suspension type insulator I2 supported from a cross arm I3 on a pole I4. A bracket I5 secured to the pole I4 and connected to ground as indicated at 20 supports the arc expulsion arrester I6. The lightning arrester comprises an insulating tube Il having a grounded electrode I8 at one end suitably secured to the supporting bracket I5 and a line electrode I9 at the oppomte end spaced by a suitable gap from the high voltage conductor I0. The insulating tube I1 includes two tightly telescoped tubes 2l and 22, at least the inner one, 2l, being of hard fiber or any other suitable material which will give oil a quantity of gas when heated by an arc discharge therethrough without itself becoming conductive. While not essential to the practice of the present invention, I prefer to coat the outer surface oi' the tube 22 with a thin coating of a high resistance semi-conductive material connecting the electrodes at the opposite end of the device, which coating is covered with a protective layer 23 oi suitable wrapping. The objects and advantages of such a high resistance coating extending between the opposite end electrodes oi'the' arrester are more fully described in my copending application, Serial No 290,855, tiled August 18, 1939, which issued on September 22, 1942, as Patent and assigned to the General Electric Company, the assignee of the present application.

An are occurring within the bore of the elonelectrodes is divided into short arcs by one or more additional electrodes arranged between the end electrodes and provision is made for the expulsion of each such arc from an immediately adjacent arc expulsion passage.

The grounded electrode I8 includes a metal tube 24 extending into an enlarged portion of the adjacent end of the inner tube 2i, the opening 25 in the tube 24 being substantially as large in cross-section as the opening of tube 2l so that the path of the gases expelled from the insulating tube may not be restricted. The electrode I8 also includes a sleeve portion 26 which is cooperatively threaded onto the end of the outer fiber tube 22 and a shoulder 2l for clamping the iiange head 28 of the electrode portion 24 against the end of a series of relatively the insulating tube. The lower end ci the electrode i8 is provided with a threaded portion 2Q or reduced outside diameter for extending through a cooperating aperture provided in the supporting bracket I to which it is secured by means of a nut 3G, the electrode Il including the threaded portion 29 being furthermore provided with an smal opening 8i communicating with the opening 25 of tube 24 and the opening through the inner tube 2i.

'Ihe line electrode il includes a tubular metal portion l! extending into an enlarged portion of the corresponding end of the inner tube 2l, the opening I4 therethrough being substantially as large in cross-section as the opening of tube Il. The electrode I9 also includes a sleeve portion 38 cooperatively threaded onto the upper end of the outer fiber tube 22, and having a shoulder $1 for clamping the ilange head Il of the electrode portion il against the end oi the insulating tube. The arc and gases expelled through the line electrode must be directed away from the supporting structure and preferably also away from the line conductor so for this purpose the line electrode includes a pair oi outwardly projecting tubular extensions and 4l communicating through the axial passage 48 .with the tube interior. Since the upper, or line electrode, end

oi the tube is unsupported, the tubular extensions are arranged diametricaily opplte from each otherin order that the reactions of the gas escaping at high velocity from the two vent passages will neutralize each other and impose substantially no lateral strain upon the tube. The upper surface of the line electrode l is provided with an extension through which is arranged an arcing horn 46 adapted to extend at right angles to the high potential line il so as to maintain a uniform gap spacing as when the transmission line is swung to and fro bythe wind.

To facilitate a rapid clearing action o1 the arrester, an intermediate electrode Il is arranged within the inner tube preferably midway between the extremities of the electrode portions 24 and Il. As shown best in Fig. 3, the intermediate electrode comprises an axially extending rod portion 52 rounded at its opposite ends and secured within a sleeve 63 by means oi a metal arcuate spacer 54 suitably brazed to both the rod and the sleeve. It will be noted that the spacer 54 extends only part way around the rod l2 so that a passage 56 is provided through the sleeve 53 te permit drainage o! water such as rain, which may ilnd its way into the upper portion of the tube 2l through the vent openings I9 and 4I downwardly through the lower vent opening 3 i While the intermediate electrode 5I may be assembled in any suitable manner within the bore or the insulating tube, I'preier to thread the outer surface oi the sleeve 53 substantially as indicated and upon which the adjacent ends or the divided inner tube 2i may be screwed in a tightly abutting relation. This construction prevents leakage of high pressure gases between the tubes 2i and 22 which might cause a rupture thereof. It will be noted that portions of the inner tube 2i are cut away slightly, as indicated at 51, so as to provide additional clearance between the electrode rod 52 and the adjacent surface of the inner tube forming reservoirs 58 and 59 in which high pressure gases are stored, during the arcingperiod while the current ilow is high. The heated gases compressed within these reservoirs during this period are augmented by unionized gases given of! from the tube wall portions 51 and as f use at 138 kv...

units are joined together by a estacas pressure between the electrodes drease, the gases will dow from the reservoirs at high velocity past the ends of the electrode iii, cooling it and facilitating the deionization and clearing oi the circuit. It will be observed that the intermediate electrode element restricts and substanhally divides the bore of the tube into two arc chambers and the arc occurring in each is rapidly ex. pelled through the discharge passage in the um. responding end electrode.

The lightning arrester assembly without the opposite end ilttings. that is. the insulating tube with the electrode portions 24 and 83 and the intermediate electrode 5| may be considered as a lightning arrester unit. Such a single unit with end nttings as shown in Fig. 2 may be rated for one voltage or a plurality of such units may be joined together in series iittings for use at higher voltage ratings corresponding to even multiples of the voltage rating for one unit. Thus, for example, assuming .that the rating for one unit as shown in Fig. 2 may be 69 kv.. then two such units may be connected together by a suitable joining iltting as shown in Fig. 5, to provide a lightning arrester suitable for l The tting used for joining two such umts together shouldinclude` vent-passages ior the expulsion of arcs fromv theadjacent ends of the two unit tubes. Y

In the modification illustrated in Fig. 5 two double ended iitting il which is similar to the upper electrode iltting il previously described in that it has a sleeve i1 for cooperatively threading onto the upper end of an insulating tube I1 and a pair of oppositely extending tubular vent passages 63 and communicating with the interior of the insulating tube by an axial passage i5. Extending from the upper portion of the electrode 8l is a second sleeve 6i in axial alignment with the sleeve 82 and substantially similar thereto. it being threaded on the inside forcooperatively receiving a second insulating tube 61 as indicated in Fig. 5.

An axial passage il in augment with the pas.

sage 65 provides communication between the interior of the tube 61 and the vent passages and I4. Thus electrodes 14 and 15 provide adjacent electrodes which extend into the tubes I'I and 81, respectively, and the electrode portion or member 8| supports the electrodes in adjacent ends of the tubes and connects the tubes in axial alignment. Obviously, any number of lightning arrester units may be combined in this manner. With the diametrically opposed arrangement of the intermediate vent passages the reactions oi the gas escaping at high velocities therethrough substantially neutralize each other so that no strains are imposed upon the midsection of the lightning arrester assembly.

As indicated in Fig. 4 it will be obvious that the electrode il may also be used at the upper end of a multiple unit assembly by closing the pasthe current and 15 the invention may be carried out by other means.

by means oi suitable y aavaoss What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising an insulating tube of gas emitting material, end electrodes extending into each o! the opposite ends of said tube, an intermediate electrode arranged within said tube and at least partially restricting the bore thereof, vent openings through the opposite ends oi said tube for arc gases, generated between said end electrodes and said intermediate electrode, said device being adapted to be supported by one of said end electrodes and with the other of said end electrodes extending adjacent a line conductor, the vent openings in the ned of said tube adjacent the line conductor being so arranged as to direct the arc gases lateraly with respect to the axis of said tube and also in such a manner that the reactive forces due to the gases being expelled substantially balance each other as regards said tube.

2. An electric discharge device comprising an insulating tube of gas emitting material, an electrode extending into each of the opposite ends of said tube, an intermediate electrode arranged within .said tube and at least partially restricting the bore thereof, and vent openings through the opposite ends of said tube for arc gases generated between said opposite end electrodes and said intermediate electrode.

3. An electric discharge device comprising an insulating tube of gas emitting material, an electrode at each end of the tube, said electrodes each having an axial opening therethrough for permitting the escape of gases from said tube, an electrode arranged in said tube intermediate said end electrodes having portions spaced from the inner walls of said tube and extending axially of said tube toward each of said end electrodes, means for ilxedly securing said last mentioned electrode in said tube.

4. An electric discharge device comprising an insulating tube of gas emitting material, an electrode at each end of the tube, said electrodes each having an axial opening therethrough for permitting the escape oi' gases from said tube, a 1ongitudinal electrode arranged in said tube intermediate said end electrodes and axially of said tube, means for supporting said intermediate electrode in a spaced relation from the inner walls of said tube.

5. An electric discharge device comprising an insulating tube of gas emitting material, an electrode at each end of said tube, a longitudinal electrode arranged within said tube intermediate said end electrodes, said longitudinal electrode being spaced -from the tube walls adjacent thereto so as to provide a reservoir thereabout for gases emitted from said tube upon the occurrence of an arc between said electrodes.

6. An electric discharge device comprising an insulating tube of gas emitting material, an electrode at each end of said tube, said end electrodes each having an opening therethrough for venting gases from said tube, an electrode secured within said tube intermediate said end electrodes, said intermediate electrede having end portions extending substantially axially within said tube and spaced therefrom, portions of said tube about said electrode end portions being enlarged to provide reservoirs for gases emitted from said tube upon the occurrence of an arc between said electrodes.

7. An electric discharge device comprising an insulating tube of gas emitting material, an electrode at each end of the tube, said electrode each having an axial opening therethrough for permitting the escape of gases from said tube, an electrode arranged in said tube intermediate said end electrodes and extending axially within said tube in a spaced relation from the inner walls thereof, a sleeve for supporting said intermediate electrode and being cooperatively threaded into adjacent portions of said insulating tube, an outer insulating tube telescopically and tightly fitted over said iirst insulating tube, said opposite end electrodes being cooperatively threaded onto the opposite ends of said outer insulating tube.

8. A lightning arrester comprising an elongated insulating tube, an electrode extending into each oi' the opposite ends of said tube, a pair of intermediate electrodes arranged within said tube in a spaced relation between said end electrodes, said intermediate electrodes each at least partially restricting the bore of said tube, an additional electrode arranged within said tube in a spaced relation between said intermediate electrodes, said tube including inner sections of gas-emitting material arranged between each adjacent pair of electrodes, said additional electrode including substantially unrestricted vent passages for the expulsion of arcs formed between it and said intermediate electrodes, and vent passages through said end electrodes for the expulsion of arcs formed between said end electrodes and said intermediate electrodes.

9. A lightning arrester comprising an elongated insulating tube, an end electrode extending into each of the opposite ends of said tube, said lightning arrester being adapted to be supported by a ilrst of said end electrodes and With the second oi' said end electrodes extending adjacent a line conductor, a pair of intermed=ate electrodes arranged within said tube in a spaced relation between said end electrodes, said intermediate electrodes each at least partially restricting the bore oi' said tube, an additional electrode arranged within said tube in a spaced relation between said intermediate electrodes, said tube including inner portions of gas-emitting material arranged between each adjacent pair of said electrodes, said additional electrode including substantially unrestricted vent passages for the expulsion of arcs formed between it and said intermediate electrodes, and vent passages through said end electrodes for the expulsion of arcs formed between said end electrodes and said intermediate electrodes, said vent passages through said additional electrode and said second end electrode being so arranged that the reactive ici-ces resulting from the expulsion or arc gases from said tube substantially balance each other .as regards said tube.

ELMER (i. WADE. 

